Ramp of discount wheelchair - http://grand-stone.kz/index.php/component/k2/itemlist/user/61612 can be customized into semi-permanent of portable one. Long-term could be done by sealing the place or bolting. Most likely semi-permanent rest at the top of the ground or cement pad and are typically - http://Www.martindale.com/Results.aspx?ft=2&frm=freesearch&lfd=Y&afs=typically used for the short-term. It builds semi-permanent and permanent usually steel or wood. Steel ramps would stand longer compared to wood but it is heavier and expensive.